Control of input devices via a keyboard interface

Details Control of input devices via a keyboard interface Control of input devices via a keyboard interface

1994-07-22

1996-04-02

Peng, John K.

Coded data generation or conversion

Bodily actuated code generator

Including keyboard or keypad

341 20, 3408253, 36470911, H03M 1100

Patent

active

055044832

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The invention relates to the connection of input devices to personal computers via an already existing keyboard interface.
2. Description of the Related Art
As a rule personal computers have a keyboard for data input for which a standard interface has emerged, as is described in IBM Personal System/2 Technical Reference Manual for example. Additional input devices are required in many application areas, for example reading devices for magnetic cards, which for cost reasons are frequently equipped with a special interface, the operation of which is time-critical. It has hitherto been necessary to use additional interfaces for these input devices on the personal computer, for example serial interfaces compliant with the V.24 standard. When personal computers are used as control units in point-of-sales terminals, for example, this however results in an additional outlay for the interface in the computer and in the unit which converts the data supplied by the magnetic card reader into that of the serial standard interface, the V.24 interface in the example, and fulfils the time conditions.
A keyboard with connected peripheral devices is described in the article entitled "Mehr als eine Tastatur" (More than a keyboard) by M. Guntner and W. Kredler, Elektronik, Issue 21, 1987, pp. 126 to 130. The data are clearly transmitted in this case from the peripheral devices via the serial V.24 interface.
Transmission via the keyboard interface is not described. Were one nevertheless to do this, the problem would arise that the keyboard controller contained in the PC would only forward such key codes belonging to previously defined keys. As a result, it is not possible to transmit all the data from the magnetic stripe without modifying the keyboard controller or reducing the data rate by means of the multiple character representation proposed in the article. Particularly in the latter case, this data can then be replaced by key operations. For the sake of reliability, and in accounting systems in particular, it is however desirable that it be possible to identify the data of the peripheral device clearly as such, and it should not be possible for the data to be simulated by key actuations.


SUMMARY OF THE INVENTION

An object of the invention is the operation of input devices at the keyboard of a personal computer which permits transmission of all the code characters of a peripheral device without reprogramming the keyboard controller in the personal computer but nevertheless does not increase the data volume. It is furthermore desirable that a simulation of the input device by key operation be precluded and a status interrogation and control of the input devices be possible.
The present invention achieves this and other objects in that the additional input device or devices are connected to the keyboard processor and send their data via the keyboard interface. The data of the input device are buffered in the keyboard processor and sent to the PC. In addition, the codes of the input devices are converted into normal key codes so that no modifications are required to the keyboard controller in the personal computer. The data of the input device are introduced by dummy key codes which cannot be generated on the keyboards used; in this way a user cannot modify or replace the data of the input devices by means of keyboard operations. However, key codes which correspond to possible keys are used so that the keyboard controller in the personal computer does not need to be reprogrammed. For this reason the binary data of the magnetic card reader are also converted into possible key codes. In order to distinguish between the data of the magnetic card reader and those of the keys, a device driver or resident filter program is required, but no reprogramming of the keyboard controller.


BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained below with reference to two exemplary embodiments.
FIG. 1 shows the design of a personal computer with two input devices connec

REFERENCES:
patent: 4774689 (1988-09-01), Morisawa
patent: 4964075 (1990-10-01), Shaver
patent: 5323153 (1994-06-01), Sonobe et al.

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